Snap action pull-push type electric switch



y 20, 1965 w. A. BARDEN ETAL 3,196,230

SNAP ACTION PULL-PUSH TYPE ELECTRIC SWITCH Filed Sept. 19, 1962 2 Sheets-Sheet 1 /2 2 25 27 FIG].

1 i 1 I 20 i r w INVENTORS JOHN D. VAN BENTHUYSEN VYAYNE A. BARDEN ATTORNEY y 20,1955 w. A. BARDEN ETAL 3,196,230

I SNAP ACTION PULL-PUSH TYPE ELECTRIC SWITCH I Filed Sept. 19, 1962 2 Sheets-Sheet 2 INVENTORS JOHN D. VAN BENTHUYSEN WAYNE A. BARDEN ATTORNEY United States Patent Thi invention relates to electric switches generally, and in particular to electric switches which can be mounted on the same shaft as a rotary adjustable component and operated without changing the setting of the component.

Switch life is usually determined by the life of its contacts. As the switch is opened and closed, arcing occurs which erodes away the contacts. Generally the faster the contacts are moved apart or into engagement the less the contacts will be damaged by arcing at each operation of the switch.

It is the principal object of this invention to provide a pull-push switch which opens and closes with an extreme- 1y fast snap action.

It is a further object and important feature of this invention to provide a pull-push switch which opens and closes at a predetermined rate of speed which is independent of the speed of the actuator of the switch.

It is another object of this invention to provide a pullpush electric switch wherein the force between the contacts increases to a maximum just before actual breaking of contact occurs to substantially increase the life of the contacts.

Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly the invention comprises a pull-push switch having a U-shaped movable contactor which is moved into and out of engagement with a pair of stationary contacts by the action of a coiled spring which is compressed between the two upright arms of the U-shaped contactor. Since the spring is not held, except at its ends, it will inerently assume a bowed shape rather than stay compressed along a straight line between the two arms of the contactor. An actuator engages the center of the bowed portion of the spring which when reciprocated back and forth, causes the spring to bow toward and away from the stationary contacts. When the spring is bowed to ward the stationary contacts, the ends of the spring are away and thus the contactor is held out of engagement with the stationary contacts. When the spring is bowed in the opposite direction, the ends of the spring are adjacent to the stationary contacts and the switch is closed.

This arrangement of parts produces the unique feature that the cont-actor remains either in or out of contact with the stationary contacts until the spring is forced slighly beyond the dead center position by the actuator at which time the spring snaps to the oppositely bowed position due to its own resiliency and without requiring any further movement of the actuator by the operator. This movement of the ends of the spring from one position to the other occurs extremely fast which greatly reduces the arcing present when a switch is opened and closed. In other words, the motion of the U-shaped contactor snaps into the open or closed position as soon as the coiled helical spring is moved slightly beyond the dead center line of the spring.

Another important feature of the invention is the fact that when the switch is being opened, the force between the contacts will be increased up to the time that the ddddiiid ll 'atented 2%}, i965 a as spring snaps to its opposite position which is just the opposite of most conventional switches and which greatly increases the life of the contacts.

The invention will be more fully understood when con sidered in connection with the detailed description set out below and the attached drawings in which:

FIGURE 1 is a fragmentary vertical section taken through a pull-push switch illustrating the position of the spring and contactor when the switch is closed;

FIGURE 2 is a fragmentary vertical section through the pull-push switch illustrating the position of the spring and contactor when the switch is opened;

FIGURE 3 is a fragmentary sectional view taken along line 3-3 of FIGURE 1, assuming that Fi-GURE 1 is shown in full; I

FIGURE 4 is a sectional view taken along line 4- of FIGURE 2, assuming that FIGURE 2 is shown in full; and

FIGURE 5 is a slightly reduced bottom plan view of the switch shown in FIGURE 3 of the drawings, assuming that FIGURE 3 is shown in full.

The switch comprises a cup-shaped housing ll generally of molded construction. in the switch shown in the drawing, the housing is triangularly shaped (see FiGURE 5) which is a conventional way to provide clearance at three places to allow it to be attached to the housing of another control. The housing is equipped with slots in the bottom portion to receive stationary terminals 11 and 12. These stationary terminals are identical cornprise solder lugs 13 and 14- and bifurcated heads i5 and 16. Each terminal has a flange portion 17 which engages the bottom of the housing it Each of the terminals is then staked at ill, as illustrated in FIGURE 3, to securely attach it to the housing it).

Electrically connecting the two terminals 1 and 12 when the switch is in the closed position is a contactor 13 which engages the bifurcated heads of both terminals as shown in FIGURE 3. T he contactor i8 is U-shaped and comprises a bight portion having an opening 19 therein and upright arms 29 and 21 are integrally attached thereto. Each arm is provided with an indentation 532 and 23 in which the looped ends 25 and 2d of the coiled spring 2 3 are located. As illustrated in the drawings, the coiled spring 24 has a free length greater than the distance between the upright arms 2% and 21 so that it will bow either in one direction or the other. The configuration of the looped ends 25 and 26 and the indentations Z2 and 23 is such that the spring will tend to bow in a plane normal to the bight portion of the U-shaped contactor 18.

The coiled spring passes through an opening 25 in the actuator 27 centrally located between the upright arms of the contactor. The actuator is also equipped with a T- shaped slot 2 which is designed to receive the end of the shaft 36 which has a turned down section 32 so that it can pass into the T-shaped slot 29 in the actuator. The end 31 of the shaft once in position in the Tshaped slot in the actuator will enable the shaft to transmit reciprocating motion to the actuator.

Mounted within the cuo-shaped housing are two partitions 34 and 35 which h. ve grooves 35 and 37 formed therein to provide a track for guiding the actuator as it is reciprocated back forth by the shaft 3%). A groove 38 is also provided in the bottom wall of the housing llfi which tends to stabilize the actuator when the switch is in the open position.

The housing lti is attached to a cover 39 which could vbe the cover of any rotatable type component such as a variable resistor having a contact carrier arranged to be rotated by the list sided portion of the shaft The type of component with which this switch is used forms no part of the invention since the switch can be attached to any rotatable component-where it is desirable to operate a switch without affecting the setting of the component, It also could be used independent of any control bysirnply extending the actuator sufficiently for it to be operated outside the housing 16. i

in operation the switch, for example, is in the position illustrated in FiGURE l with the contactor 35.8 engaging the biturcated heads 45 and is of the stationary cont-acts i1 and 12. shaft 3% inwardly forcing the actuator and. the coiled spring toward the position shownin FIGURE 2. As the coiled spring approaches the point where it will snap to the position indicated FIGURE 2, the force being exerted on the coiled spring by the actuator is transmitted to the contact portions of the contactor and to the heads of the stationary contacts. This force continues to increase the pressure existing between the contact portions and the stationary contacts until the coiled spring reaches dead center and, as the spring is urged slightly beyond dead center or the critical point, the spring flexes or snaps instantaneously to the position indicated in 2 at which time the engagement between the stationary contacts and the contact portions of the contactor is broken.

As mentioned above this is one of the important features of this invention in that the movement of the contactor is independent of the rate of speed of movement of the actuator and, as the shaft is being moved inwardly to open the switch,'the pressure between the contacts is actually increased up to the point of opening of the switch rather than decreased as is generally the case.

To close the switch the shaft is returned to the position shown in FIGURE 1, with the contactor being snapped back into engagement with the stationary terminals by the spring in the same manner as it was snapped out-of engagement when the switch was opened. v t

While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be appreciated that numerous changes and modifications are likely to occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention, 1

The invention claimed is:

1. An electric switch comprising a housing, a pair of stationary contacts mounted in the housing, a movable U-shaped contactor having a pair of contact portions abuttingly engageable with the stationary contacts and displaceably mounted in the housing, the distance between the contact portions being greater than the inside dimension between the stationary contacts, a coiled spring hava pair or" ends supported by the contactor, the ends being spaced apart a distance lessthan the free length of the spring causing the spring to assume a bowed shape, an actuator engaging the coiled spring, a reciprocable shaft, means operatively connecting the shaft to the actuator whereby axial movement of the shaft moves the contactor into and out of engagement with the stationary contacts, a pair of partitions disposed within the housing for guiding the U-shaped contactor, and guide means provided on the partitions for guiding the actuator in the housing.

2. An electric switch comprising a cup-shaped housing having a base portion, a pair of stationary contacts mounted in the base portion of the housing, a movable U-shaped contactor having a pair or" contact portions abuttingly engageable with the stationary contacts, the cont actor being displaceably mounted in the housing, the distance between the contact portions being greater than the inside dimension between the stationary contacts, a spring, means integrally connected to the contactor for carrying the spring, the ends of the spring being spaced apart a distance less than the free length of the spring ing ' by therneans connected to the contactor causing the spring to assume a bowed shape, and an actuator engaging the bowed portion of the spring, the actuator being To open the switch the operator moves the displaceably supported by the housing and defining a path substantially normal to, the axis of the spring whereby upon moving the actuator to disengage the U-shapcd contactor from the stationary contacts the force exerted by the actuator increases the pressure of the contact portions of the contactor against the stationary contacts until the instant that the contactor is urged away firom the stationary contacts.

3. An electric switch comprising a cup-shaped housing, a pair of stationary contacts fixedly secured in the housing, a movable U-shaped contactor facing the stationary contacts and slideably mounted in the housing, the movable U-shapcd contactor having a base portion and a pair of spaced upstanding arms integral with the base portion, the base portion of the movable U-shaped contactor being provided with a pair of contact ortions and having a dimension greater than the spacing between the station ry contacts for abuttingly engaging both of the contacts simultaneously, a coiled helical spring supported by the movable U-shaped contactor, the ends of the spring being spaced apart a distance less than the free length of the spring by the movable U-shaped contactor causing the spring to assume a bowed shape, and an actuator engaging the bowed portion of the spring, the actuator being displace ably supported by the housing and defining a path substantially normal to the axis ofthe spring whereby I upon moving the actuator to disengage the U-shaped contactor from the stationary contacts the force exerted by the actuator increases'the pressure of the contact portions against the stationary contacts until the instant that the contactor is urged away from the stationary contacts.

2. An electric switch comprising a housing, a pair of stationary contacts in the housing, a movable contactor having a pair of contact portions abuttingly engageable with the stationary contacts and displaceably mounted in the housing, the distance, between the contact portions einggreater than the inside dimension between the st' tionary contacts, the movable contactor being provided with a cutout portion, a movable actuator disposed in the housing, a spring passing through an opening in the actuator, a pair of spaced spring support means on the movable contactor supporting the end portions of the spring, the distance between the pair of the spaced spring support means on the movable contactor being less than the 'free length of the spring causing the spring to assume a bowed shape, a pair of partitions disposed within the housing, and guide means provided On the partitions for guiding the actuator, the actuator moving in a path substantially perpendicular to the axis of the spring, a portion of the actuator being movableinto and out of the cutout portion.

5. An'electric switch comprising a housing, a pair of stationary contacts in the housing, a movable contactor facing the stationary contacts and displaceably mounted inthe housing and having a base portion and a pair of upstanding arms integral with the base portion, the base portion of the movable contactor having a dimension greater than the spacing between the stationary contacts for 'abuttingly engaging both of the contacts simultaneously, the base portion of the movable contactor being provided with a cutout portion, a spring supported by the movable contactor, the distance between the ends of the spring being less than the free length of the spring causing the spring to assume a bowed shape, an actuator engaging the bowed portion ofthe spring, and guide means provided in the housing for guidingthe actuator, the actuator being displaceably supported by the guide means and defining a path substantially normal to the'axis of the spring, a portion of the actuator being movable into and out of the cutout portion.

6. An electric switch comprising a housing, a pair of spaced stationary contacts disposed in the housing, a U-shaped contactor having a pair of contact portions displaceably mounted in the housing and movable into and out of engagement with the contacts, a pair of partiti-ons disposed within the housing for guiding the U- shaped cont actor, reciprocable actuating member disposed in the housing and provided with an opening, guide means carried by the partitions for guiding the actuating memher in the housing, a spring passing through the opening in the actuating member, and a pair of spaced spring support means on the U-shaped contactor supporting the end portions of the spring, the spring having a free length greater than the distance between the pair of spaced spring support means.

7. The electric switch of claim 6, wherein a rotatable shaft is connected to the actuating member, and axial movement of the rotatable shaft moves the contactor into and out of engagement with the stationary contacts.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS Germany.

BERNARD A, GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner. 

1. AN ELECTRIC SWITCH COMPRISING A HOUSING, A PAIR OF STATIONARY CONTACTS MOUNTED IN THE HOUSING A MOVABLE U-SHAPED CONTACTOR HAVING A PAIR OF CONTACT PORTIONS ABUTTINGLY ENGAGABLE WITH THE STATIONARY CONTACTS AND DISPLACEABLY MOUNTED IN THE HOUSING, THE DISTANCE BETWEEN THE CONTACT PORTIONS BEING GREATER THAN THE INSIDE DIMENSION BETWEEN THE STATIONARY CONTACTS, A COILED SPRING HAVING A PAIR OF ENDS SUPPORTED BY THE CONTACTOR, THE ENDS BEING SPACED APART A DISTANCE LESS THAN THE FREE LENGTH OF THE SPRING CAUSING THE SPRING TO ASSUME A BOWED SHAPE, AN ACTUATOR ENGAGING THE COILED SPRING, A RECIPROCABLE SHAFT, MEANS OPERATIVELY CONNECTING THE SHAFT TO THE ACTUATOR WHEREBY AXIAL MOVEMENT OF THE SHAFT MOVES THE CONTACTOR INTO AND OUT OF ENGAGEMENT WITH THE STATIONARY CONTACTS, A PAIR OF PARTITIONS DISPOSED WITHIN THE HOUSING FOR GUIDING THE U-SHAPED CONTACTOR, AND GUIDE MEANS PROVIDED ON THE PARTITIONS FOR GUIDING THE ACTUATOR IN THE HOUSING. 